Method of producing intaglio printing forms



Nov. 22, 1932. K. WOLFSOHN METHOD OF PRODUCING INTAGLIO PRINTING FORMSFiled Dec. 50, 1929 my. a

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M/VEA/ 70f? 1/197- W0LF50/m Arm/m5) I Patented Nov. 22, ,1932

UNITED STATES PATENT OFFICE KURT WOLFSOHN, '01 SGHOENEBEBG, NEAR BERLIN,GERMANY, ASSIGNOR TO ltOTOPHO'II FUEB GRAPHISCHE INDUSTRIE, OF BERLIN,GERMANY METHOD OF PRODUCING INTAGLIO PRINTING FORMS Application filedDecember 30, 1929, Serial :0. 417,698, and in Germany June 21, '1929.

The present invention relates to a process for the manufacture ofendless intaglio printing formes or plates for printing paper, textilematerials, oil-cloth, linoleum and similar materials. Endless intaglioformes or plates for printing paper and similar materials are alreadyknown. The pattern to be reproduced has heretofore been copied on alight-sensitive, preferably screened pig- 1o 'ment gelatine paper, suchas carbon tissue backed with paper and the copy was then transferred tothe metal support and developed. Since the transference was not possiblewithout a so-called securing edge, the pattern' could not be applied totheperiphery of the endless intaglio forme without a break. The transferof the pattern by means of the above-mentioned pigment gelatine etchingprocess must therefore take place in at least two successive operations;first the one half of the pigment paper had to be. applied to theintaglio 'forme developed and this part. etched and finished, and thenthe other half had to be applied to the endless intaglio forme andtreated in a similar manner. The half of the cylinder which was etchedand finished first was covered with a protective coat of varnish beforethe second half was etched. When carrying out the process it was foundto have a serious disadvantage namely that the two etchings were almostalways not uniform. The process was particularly difiicult to carry outin the case of patterns exhibiting a long range of shades covering theentire surface of the intaglio forme and having a uniformly bright tonewhich forms as it were the ground work of the pattern to which theremaining elements of the pattern are applied. Even if the successivelyetched portions were subjected to a subsequent etching process which wasdifiicult to carry out, complete uniformity in the portions of theetchings was hardly ever obtained, so that in most cases severaletchings had to be rejected, before two etchings which matched after afashion were obtained.

In contra-distinction thereto the novel feature of the present inventionconsists in com- 50 bining the parts of the etching ground or resist onthe endless forme or cylinder before either part is etched and thencarrying out the etching in a single operation. In order to produce theendless resist covering the securing edge of each part of the resistcovermg is removed, for example by cutting it off, before theapplication of any further ad- ]oining part of the resist covering andthe securing edge of the last part which comgletes the resist coveringis also removed.

efore removing their securing edges the pertaining parts of the resistcovering are preferably covered by a medium, for example varnish, whichprotects their surface. After the application of the last portion whichcompletes the endless resist covering the edge of which is also removed,preferably after it has been covered with a protecting coating, theprotecting medium is removed from the endless resist covering, forexample by the use of a solvent for the varnish, and the etching of theendless resist which has been prepared in this manner is carried out ina single operation.

The accompanying drawing illustrates the manner of carrying out thepresent invention; in said drawing,

' Fig. 1 shows a printing cylinder having one-half of a film appliedthereto;

Fig; 2 is a top plan view of Fig. 1;

Fig. 3 shows a cylinder on which the first half of the film has beencutand trimmed, and the second half of the film positioned upon the otherhalf of the cylinder;

. Fig. 4 illustrates in plan the cylinder shown in Fig. 3;

Fig. 5 is a view showing the cylinder with the two halves of the film inproper position thelreon and ready for the etching treatment; an

Fig. 6 shows a plan view of the finished cylinder shown. in Fig. 5.

The numeral 1 indicates a copper c linder which is to be provided withan end ess intaglio pattern for the printing of paper, textiles,oilcloth, linoleum, and similar materials. In accordance with thepresent invention the cylinder 1 is provided with a continuous endlesspattern free of breaks or irregularities in the following manner. A 100selected portion of the pattern, two securing edges 5 and 6. The part 2of the film, which,

as stated, contains a definite portion of they pattern, is then boundedby two curved or irregular lines 3-3, 4-4; These bounding or limitinglines are clearly shown in Figs. 2, 4 and 6, which illustrate plan viewsof the cyl-- inder at the various stages of the process, only the lines3-3 being visible, the lines 4-4 being at thezunderside of the cylinderas shown in Figs. 1, 3 and 5. Figs. 1 and 2 show the steps of theprocess in which the part 2 of the film is covered with the protectingvarnish 7. After the application of the varnish, the securing edges 5and 6 of the developed, protected film are either lightly cut off with asharp knife without injuring the cylinder, and the superfluous filmpulled off dry, or they are moistened and then pulled off. It is ofadvantage to coat the varnish layer 7 with a solution of a colloid(chromate-albumin, gelatine, dextrin), to which metallic salts, such asaluminum sulfate, may be added, in order to secure a better adhesion ofthe second transfer.

The film section containing the rest of the pattern is now positionedupon the cylinder 1. This second film is composed of a portion 8 whichcontains the remainder of the pattern, and the two securing edges 9 and10. As the portion 8 of the second'film is bounded by the curved orirregular lines 3-3 and 4-4, like the portion 2 containing the othersection of the pattern, it is only necessary so to position the film 8,9, 10 upon the cylinder that the lines 3-3 and 4-4 of the parts 2 and 8coincide in order properly to join up the two parts of the pattern. Thesecond part of the pattern is now developed and after drying is coveredwith a coat of varnish 11. This phase of the process is illustrated inFigs. 3 and 4. The overlapping securing edges 9 and 10 which cling tothe first varnish coating 7 with the aid of the colloidal solution, arenow removed. In this way the two film portions 2 and 8 are joined into acontinuous film lying upon the surface of the cylinder and containing anendless pattern. This step in the process is illustrated in Figs. 5 and6. The cylinder which has been provided in this manner with an endlessresist covering is then freed from varnish by washing with a solvent forthe varnish, such as benzol after which the etching of the cylinder iscarried out in a single operation. Any dilferences in the height of therelief, as are always possible owing to variations in light or theinfluence of weather, can at once be equalized by the employment ofsuitable etching solutions, since the progress of the etching on theperiphery of the printing cylinder which has been prepared in accordancewith the invention can be controlled continuously. The result of theprocess is an endless intaglio printing forum or plate which is quiteuniform in the gradations of tone, such as could not be obtained by thehitherto usual method of successive partial etchings.

It will be understood that, while I have described my invention inconnection with a cylindrical printing form, my invention is equallyapplicable to any other body of revolution, such as a cone or a frustumof a cone. lVben, therefore, I employ in the claims the expressioncircular intaglio printing forms, I intend to include thereby all typesof bodies of revolution.

I claim 1. Process for the manufacture of circular intaglio printingforms which comprises transferring parts of a picture or pattern to alight-sensitive screened, pigment film, applying the pigment film to thesurface of the printing cylinder, developing it, coating it with amedium which protects its surface, removing its securing edge, combiningthis portion of the resist covering similarly with further portionswhich fit on to and adjoin the adjacent portion so as to form an endlessresist, removing the protecting medium from the endless resist and thenetching in a single process of operation.

2. Process for the production of circular intaglio printing forms whichcomprises transferring portions of the picture or pattern on to alight-sensitive, screened pigment gelatine film, applying the film tothe surface of the printing cylinder, developing it, coating its surfacewith a protecting film of varnish and the film of varnish with acolloidal solution, removing the securing edge of the said pigmentgelatine film, combining this portion of the resist covering in asimilar manner with further portions which fit on to the adjacentportion so as to form an endless resist, removing the varnish andcolloidal films from the endless resist and then etching in a singleprocess of operation.

3. In a process for the production of circular intaglio printing forms,the steps which comprise applying to the form in succession a pluralityof resist covering sections each provided with a securing edge, removingthe securing edge of each part before the application of the nextadjoining section of the covering, then removing the securing edge ofthe last section applied and thereby completing the endless resistcovering, and then etching the cylinder in a single treatment.

, 4. In a process for the production of circular intaglio printingforms, the steps which comprise applying to the form in succession aplurality of resist covering sections each provided with a securingedge, coating each part of the resist covering with a medium whichprotects its surface and removing its securing edge before theapplication of the next adjoining section of the resist covering,removing the securing edge of the last portion applied and therebycompleting the endless resist covering, removing .the protecting medium,and then etching the cylinder in a single treatment.

5. In a process for the production of cir cular intaglio printing forms,the steps which comprise applying to the form in succession a pluralityof resist covering sections each provided with a securing edge. coatingeach section of the resist covering with a medium which protects itssurface and removing its securing edge before the application of thenext adjoining section of the resist covering, coating the last sectionof the resist covering with such protecting medium and removing itssecuring edge, removing the protect- 7 ing medium and then etching thecylinder in a single operation.

6. In a process for the production of circular inta-glio printing forms,the steps which comprise producing a resist photographical- 1y upon aplurality of transfer sheet sections whose total effective length alongany line is equal to the circumference of the form along a correspondingline, mounting such sections in succession upon said form to form anendless covering, and subsequently etching the Whole formsimultaneously.

7. Ina process for the production of circular intaglio prnting forms,the steps which comprise producing a resist photographically upon aplurality of transfer sheet sections whose total effective length alongany line is equal to the circumference of the form along a correspondingline, mounting each section separately and developing the same beforethe next section is mounted, until an endless resist covering isproduced, and subsequently etching the whole'form simultaneously.

In testimony whereof I haves'igned mywaif name to this specification.

KURT WOLFSOHN.

